Improvement in tubular bridges



diluted 51am aient e dtiirc.

` Letters Patent No. 108,663, dated October 25, 1870.;

IMPROVEMENT IN TUBULAR BRIDGES.

The Schedule referred toin these Letters Patent and making part of the same.

To all whom 'it may concern Beit known that I, GEORGE 1I. Wurzen, of the city, county, and State of New York, have invented a new and useful Improvement in Tubular Bridges; and I do herebydcclare that the following is a-t'ull, clear, and exact description thereof, which will enable others skilled in the art to make and use the same, reference being had to the accompanying drawing forming part ot' this specification.

This invention relates to tubular bridges, and consists in certain improvements thereon which will be specified hereinafter.

In the accompanying drawing- Figure l represents a vertical longitudinal section of the bridge, showing the frame-work at its extremi ties and the abutments on which it is supported, the section being on the line :n :v of fig. 2.

Figure 2 is a vertical cross-section of iig. 1, on the line y y.

Figure 3, plate 2, represents a top view of the bridge.

Figure 4 is a vertical cross-section on the line z 5 of iig. 3.

Similar letters ot' reference indicate corresponding parts.

This bridge is constructed by combining two sets of longitudinal or horizontal ribs with a series of vertical ribs, and a set of radial ribs set edgewise, or ou a radial line from the-center to the circumference of the tube, the whole being surrounded by two series of spiral ribs, which act both as ties and braces.`

Beneath the spiral ribs, and before theyare adjusted, I-apply to the upper Aportion of the arch, throughout the length of the bridge, diagonal braces, securely bolted or riveted to the radial ribs before mentioned and to the vertical ribs.

A represents the tube in which the track or roadway is laid, which in crosssection is designed to be a true circle7 formed by the interior 'seriesl of longitudinal ribs B, which are fastened to the interiol' of vertical ribs C, by means of' knees' or angleirons,as sceu at D i'n the drawing.

E represents the other series of longitudinal ribs, which is fastened in the same lnauner to the outer edges of the vertical ribs G.

F represents the knees or angle irons by which they arey fastened.

G- represents the radial ribs, which, like-those men d tioned, extend the entire length ofthe bridge. rllhey are let into slots out in the vertical ribs, and are fastened, like the other longitudinal ribs, at each intersection with the vertical ribs C, by angle-irons, as seen in the drawing.

lhc bridge is arching on all sides, from one end to the other, but the upper portion or crown, 1which is strengthened and partially supported bythe radial ribsG, is about twice the distance from the center ot' the tubo that the bottom and sides are. 'This formation is plainly seen in the longitudinal section, tig. 1, thus providing for au amount' of vertical pressure vastly 'above what the base-tube, or what aV simple round tube, constructed lin any manner, would sustain.

In tig. 3,'plate 2, `a port-ionv of the upper arch is seen, provided with diagonal lbraces H. This system Y of bracing is continued the entire length of the arch, and occupies the space between the two outer radial ribs and the vertical ribs. i

J represents the spiral ribs, of which there are two series, passing in opposite directions, each making about one turn or revolution around the structure.

lhese ribs are securely boltedlor riveted-'together y wherever they intersect. They are also rmly boltedl or riveted to the outerlongitudinal ribs E.

At the ends of the structure the longitudinal, as

ribs arching on all sides, it -will be seen that every rib lof the inner tube is a chord of the arch.

The structure is designed to be made of either wood or metal, the sizes or dimensions of the several ribs and braces being determined by the span of the bridge and the purpose for which it is designed.

It -is believed that this is the best disposition that can be made of either metal or wood, in the forma- .tion of a tubular bridge, and its advantages over'siln-` ilar structures made of boiler or other sheet or plate.-

iron, or of wood, must be obvious to all who understand the subject.

I am aware that attempts have been made to coustruct tubular bridges by a simple lattice-work formed of either iron or wood, with an interior roadway vof rectangular for-1n, and interior bracing; but; I am not aware that tubular bridges have been constructed inA the arch form.

In my improvement the longitudinal ribs is the I essential feature'. The spiral ribs, being combined with them, and assisting to strengthen the arch, and the whole rigidly connected together at the ends and to tbe frame-work K, as heretofore described, distinguishes my structure from anything czfthe kind herc-` tiofore presented to the public.

Having thus described my invention,

I claim as new, :ind desire to sccnre by Letters Pa-tentv l. A tubular bridge, forming a. perfect circle at any cross-section, but grztdnaily eniztrgingvin diameter from cach end toward the center, as shown and described.

2. InA combination with ordinary spiral ribs J the arc-ribs G, chord-ribs Ii, and vertical ribs C, arranged to co-opcrztte in the support of 4the structure, :is set forth.

3. In a, tnbuiar bridge, arched ribs G, supported in heavy frame-work K at each end, :ts shown and dcscribed.

GEO. WHITE.

Titncssesz GEO. W. MABEE, ALEX. F. ROBERTS. 

